1. Field of the Invention
The subject matter of the invention is a polyamide mass or composition, a process to produce the same and a process to increase the shock resistance, notched impact strength and viscosity of flameproof, halogen-free polyamides. An additional subject matter of the invention is a process to increase the mass of polyamides.
2. Prior Art
In recent times flameproof, halogen-free polyamides are becoming increasingly more important. Therein exist a particular interest for light-colored polyamides for application in the electrical branch. According to EP 0 019 768 it is known that polyamides are flame proofed by adding red phosphorus in combination with melamine cyanurate. According to EP 0 122 693 the application of a halogen-containing flameproofing agent in combination with melamine cyanurate is known.
DE-A 27 40 092 describes a polyamide resinous mass containing 21 wt. % melamine cyanurate flameproofing agent which is added to the polyamide resinous mass to prevent leaching and scaling. This addition effects a satisfactory flame resistance character and leads to a suitabiliy of the polyamide resinous mass for the production of molded objects. Furthermore the so-produced polyamide resinous mass does not tend to undergo either flattening or leaching. Under the term "scaling" the sublimation of the melamine added during the formation of the polyamide mass is to be understood; the sublimed melamine separates from the mold. This results in an undesired flaking or spotting of the molded object during aging of the same. Thereby melamine is washed out of the surface of the molded object. This phenomenon is termed "leaching". The appearance of the so-obtained molded object with respect to the formation of spots is not satisfactory.
DE-C2 32 08 486 also describes a flameproof polyamide mass treated with the reaction product of cyanuric acid with finely divided melamine.
The disadvantage of the existing state of the art is that by flameproofing polyamides with the help of melamine cyanurate, the shock resistance, notched impact strength and viscosity of the polyamide are lowered. In example 5 and Table 1 of DE C2 32 08 486 a flameproof polyamide 66 is described containing 4 wt. % melamine and 6 wt. % melamine cyanurate (1:1). According to Table 3 in example 13 of the printed publication it is to be understood that the test objects were produced from the polyamide of example 5 and compared to the corresponding non-flameproof test objects prepared from polyamide 66. According to Table 3 it is to be understood that the mechanical values of the flame resistance polyamides over the untreated polyamides are considerably deteriorated, especially the viscosity is lowered (page 7, line 33).